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NAME
     sge_commd - Grid Engine communication agent

SYNOPSIS
     sge_commd [ -S ] [ -a aliasfile ] [ -dhr ] [ -help ]  [  -ll
     loglevel ] [ -ml fname ] [ -nd ] [ -p port ] [ -s service ]

DESCRIPTION
     All network communication in a Grid Engine cluster  is  per-
     formed  via the communication daemons <I>sge</I>_<I>commd</I>. Client pro-
     grams like <B><A HREF="../htmlman1/qsub.html">qsub(1)</A></B> or <B><A HREF="../htmlman1/qstat.html">qstat(1)</A></B> as well as Grid  Engine  dae-
     mons  such as <B><A HREF="../htmlman8/sge_qmaster.html">sge_qmaster(8)</A></B> or <B><A HREF="../htmlman8/sge_execd.html">sge_execd(8)</A></B> use the service
     provided by <I>sge</I>_<I>commd</I>  in  order  to  send/receive  messages
     to/from other Grid Engine components.

     <I>sge</I>_<I>commd</I> handles an arbitrary number of concurrent synchro-
     nous  or  asynchronous communications. Usually one <I>sge</I>_<I>commd</I>
     is  started  up  automatically  on  each   host   on   which
     <B><A HREF="../htmlman8/sge_qmaster.html">sge_qmaster(8)</A></B>,   <B><A HREF="../htmlman8/sge_execd.html">sge_execd(8)</A></B>   or/and   <B><A HREF="../htmlman8/sge_schedd.html">sge_schedd(8)</A></B>  are
     invoked. It is however possible to  connect  multiple  hosts
     via  one  <I>sge</I>_<I>commd</I>  or  to  use  a <I>sge</I>_<I>commd</I> on a submit or
     administrative Grid Engine host (without running one of  the
     other  Grid  Engine  daemons) as communication agent for the
     Grid Engine client programs invoked from that host.

OPTIONS
     -S   Forces  secure  ports  to  be  used  for  communication
          between  <I>sge</I>_<I>commd</I>s  and between other Grid Engine com-
          ponents and the  <I>sge</I>_<I>commd</I>s.  This  requires  all  Grid
          Engine  daemons  to be started with root permission and
          the client programs to be configured set-uid  root.  In
          turn,  it  ensures  that  unauthorized communication is
          prohibited for non-root accounts.

     -a aliasfile
          A file containing Grid Engine host aliases used by  the
          <I>sge</I>_<I>commd</I>  to  resolve Grid Engine unique hostnames for
          all hosts in the cluster. Overrides the  usage  of  the
          default         host_aliases         file         under
          &lt;<I>sge</I>_<I>root</I>&gt;/&lt;<I>cell</I>&gt;/<I>common</I>/<I>host</I>_<I>aliases</I>.   The   hostname
          resolving  service  of  <I>sge</I>_<I>commd</I>  is  also used by all
          other Grid Engine components.  The file format and  the
          implication    of    its   usage   are   described   in
          <B><A HREF="../htmlman5/sge_h_aliases.html">sge_h_aliases(5)</A></B>.

     -dhr The hostname resolving  C-library  functions  (such  as
          <B><A HREF="../htmlman3/gethostent.html">gethostent(3)</A></B>,  <B><A HREF="../htmlman3/gethostbyname.html">gethostbyname(3)</A></B>  and <B><A HREF="../htmlman3/gethostbyaddr.html">gethostbyaddr(3)</A></B>)
          perform some kind of caching on some OS  architectures.
          Network wide hostname databases distributed by services
          such as DNS (Domain  Name  Service)  and  NIS  (Network
          Information  Service)  are  updated  with  a  delay  of
          several minutes. This only affects  applications  which
          repeatedly  resolve  hostnames  (such as <I>sge</I>_<I>commd</I>). At
          start-up of a program the most  recent  information  is
          accessed,  thus  commands like <B><A HREF="../htmlman1/telnet.html">telnet(1)</A></B> or <B><A HREF="../htmlman1/nslookup.html">nslookup(1)</A></B>
          are not affected.
          However, for <I>sge</I>_<I>commd</I> it makes  no  sense  to  resolve
          hostnames  anytime (the returned information may be out
          of date anyway)  and  resolving  can  be  an  expensive
          operation  if  the  network is overloaded and/or NIS or
          DNS  servers  are  very  busy.   Therefore,   <I>sge</I>_<I>commd</I>
          resolves hostname information from time to time only.
          Yet, if hostname resolving still causes problems due to
          network  load,  for  example, it can be turned off with
          the -dhr switch.  The administrator has  to  be  aware,
          that if the hostname resolving is turned off, <I>sge</I>_<I>commd</I>
          has to be restarted as soon as the  hostname  databases
          change significantly.

     -help
          Prints  a listing of all options.

     -ll loglevel
          Sets a logging level for error tracing. The error trace
          information      is     written     to     the     file
          /<I>tmp</I>/<I>commd</I>/<I>err</I>.&lt;<I>pid</I>&gt;. However, the directory /<I>tmp</I>/<I>commd</I>
          must  be  present, otherwise the tracing output is dis-
          carded. At present,  255  is  the  only  valid  logging
          level.

     -ml fname
          Enables message logging to file.

     -nd  Do not daemonize. If started with -nd, <I>sge</I>_<I>commd</I>  main-
          tains  its  connection  to the controlling terminal and
          thus outputs trace information directly to the terminal
          from which <I>sge</I>_<I>commd</I> was invoked. The trace information
          is the same as being accessible via the -ll option (see
          above).

     -p port_number
          Use this TCP port for communication with other commds.

     -s service_name
          Use this service name and thus the associated TCP  port
          for communication with other commds.

ENVIRONMENTAL VARIABLES
     SGE_ROOT       Specifies the location  of  the  Grid  Engine
                    standard configuration files.

     COMMD_PORT     If set,  specifies  the  tcp  port  on  which
                    <I>sge</I>_<I>commd</I>  is expected to listen for communi-
                    cation requests.  Most installations will use
                    a  services  map entry instead to define that
                    port.

     COMMD_HOST     (Does not affect the  behavior  of  <I>sge</I>_<I>commd</I>
                    but  of the other Grid Engine components con-
                    tacting <I>sge</I>_<I>commd</I>.)  If  set,  specifies  the
                    host  on which the particular <I>sge</I>_<I>commd</I> to be
                    used for Grid Engine communication  of  arbi-
                    trary  Grid Engine client programs or daemons
                    resides. Per default the local host is used.

RESTRICTIONS
     <I>sge</I>_<I>commd</I> usually is invoked by  a  starting  <B><A HREF="../htmlman8/sge_qmaster.html">sge_qmaster(8)</A></B>
     and  <B><A HREF="../htmlman8/sge_execd.html">sge_execd(8)</A></B> and thus is running under root permission.
     If started by a normal user the -S switch may not be used as
     the secure mode requires root permission (see above).

SEE ALSO
     <B><A HREF="../htmlman1/sge_intro.html">sge_intro(1)</A></B>,        <B><A HREF="../htmlman5/sge_h_aliases.html">sge_h_aliases(5)</A></B>,         <B><A HREF="../htmlman8/sge_execd.html">sge_execd(8)</A></B>,
     <B><A HREF="../htmlman8/sge_qmaster.html">sge_qmaster(8)</A></B>, <B><A HREF="../htmlman8/commdcntl.html">commdcntl(8)</A></B>.

COPYRIGHT
     See <B><A HREF="../htmlman1/sge_intro.html">sge_intro(1)</A></B> for a full statement of rights and  permis-
     sions.




























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